1. Field of the Invention
The present invention relates to a system and method for re-locating an object in a sample on a previously-examined slide with a microscope imaging device.
2. Description of Related Art
Microscopic analysis is a widely used tool for research and routine evaluations, particularly in the field of cellular biology, cytology and pathology. Tissue samples and cell preparations are visually inspected by pathologists under several different conditions and test procedures, through the use of a microscope. Based on such a visual inspection by the pathologist, determinations concerning the tissue or cellular material can be made. For example, in cancer detection and research, microscopic analysis aids in the detection and quantification of genetic alterations and/or anomalies that appear related to the cause and progression of cancer, such as changes of expression of specific genes in form of DNA or messenger RNA (gene amplification, gene deletion, gene mutation), or the encoded protein expression. These alterations/anomalies can either be assessed in microscopic slides specifically prepared to present individual cells, as is the standard procedure in cytology, or whole histological sections or Tissue Micro Arrays can be evaluated.
Although numerous other suitable laboratory techniques or analyses exist, microscopy is routinely used because it is an informative technique, allowing rapid investigations at the cellular and sub-cellular levels, while capable of being expeditiously implemented at a relatively low cost. However, in order to overcome, for example, subjectivity and/or repeatability limitations of conventional microscopy, improved analysis devices combine the microscope with automatic image analysis provisions. Such improved devices include, for example, interactive systems, automatic scanning devices, and virtual slide scanners.
Interactive systems usually don't change the workflow of the pathologist analyzing and interpreting slides underneath the microscope. Typically, such interactive systems allow the potential for extracting additional quantitative information from the slide via image analysis and, therefore, possibly improve the reproducibility and the interpretation results of the operator. Better tools for reporting and documenting analysis results may also be realized. If properly configured, interactive systems are relatively fast and cost efficient, but the impact of such interactive systems on routine workflow is relatively small.
Automatic rare event detection devices are typically set up in a way that the whole analysis of the slides is done by the system in a totally unsupervised manner, from the loading of the slides onto the scanning stage to the final reporting of the results. Such automatic systems usually scan the slides, automatically identify objects or areas of interest for the analysis, quantitatively assess the targets, and report and document the results. The routine workflow for the pathologist or cytotechnologist in general is changed drastically, from a labor-intensive screening task to the interpretation of analysis results. However, such automatic systems are normally quite expensive, so that a relatively high annual volume of slides must be processed to cost-justify the acquisition of such a device.
Virtual slide scanning systems have been developed to automatically acquire large overview images at different optical resolutions. Such overview images can be far larger than the individual FOVs as they can be seen in the microscope.
One common device-independent factor relating these three applications mentioned above, namely interactive systems, automatic scanning devices, and virtual slide scanners, is that there may be instances in which the previously scanned, imaged, and/or otherwise analyzed slide must be physically re-examined by an operator. In such instances, the operator is faced with the task of re-locating an object of interest in the sample on the slide, wherein such an object of interest was discovered in the previous analysis of that slide. To compound the task, the operator may, in some instances, be using a different microscope imaging device from the microscope imaging device or other apparatus that was previously used to scan, image, and/or analyze that slide. In some instances, the magnification used to previously image or analyze the slide may not be known, and the device used by the operator may have a different resolution, both in terms of imaging capacity as well as in terms of movement provision of the device components.
In a typical method of re-locating an object in a sample on a slide, one or more re-location marks are designated and located on the slide, and these marks stored as reference coordinates, prior to the slide being scanned or otherwise imaged. During the slide scanning procedure, one or more images of the slide or objects within the sample on the slide are captured and stored, possibly with coordinate values that are determined relative to the relocation marks. Before reviewing or otherwise attempting to re-locate an object on the slide, one or more of the re-location marks must be found on the physical slide. If the appropriate functionality is provided, the operator may be allowed to select a desired object of interest from a visual display of objects of interest in the sample, at which time the stage moves to an expected or estimated location where the selected object should be within the field of view. However, the operator may have to subjectively identify whether the object at the expected location is the same as the object selected by the operator. The operator also must often manually correct the stage position if the displayed object is off-center with respect to the field of view. In addition, if the selected object is not displayed or cannot be otherwise identified in the field of view at the expected position, then the operator generally must manually find the object. However, once a manual search procedure is invoked by the operator, any coordinate calibration is usually lost and any objects later selected for review will require the same time-consuming manual relocation procedure to be performed by the operator.
As such, typical re-location methods often require specific slides having precision marks particularly for the re-location procedure. Further, expensive high-precision (typically in the micron range) motorized stages are often necessary for capturing and/or re-locating objects on the slide so as to maintain sufficient reproducibility with respect to the previously-scanned image over the entire extent of the slide. Prior to scanning the slide, the re-location marks or other parameters must be established by physically finding those marks on the slide, wherein such re-location marks again have to be found prior to reviewing the slide so as to re-locate objects of interest. If the re-location methodology is not sufficiently accurate, the location of a selected object may have to be manually corrected to bring that object into proper position in the field of view. Also, locating one object generally does little if anything to improve the re-location precision for subsequently-selected objects of interest on that slide. Still further, re-location precision is dependent on the precision of the scanning stage, as well as the precision of the review stage, and may also be affected by the preciseness of the determination of the re-location marks during both the scanning and re-location procedures.
Thus, there exists a need for a method and apparatus for rapid and efficient re-location of an object of interest in a sample on a previously-scanned microscope slide under a microscope imaging device, wherein minimal, if any, manual intervention of the operator is required, particularly where the microscope stage is motorized and the microscope thus capable of automatically performing most if not all re-location functions. Such a method and apparatus should desirably be capable of re-locating the object whether or not the slide was scanned by that device or a different device. Such an apparatus and method should desirably be relatively cost effective, have relatively little and/or simple equipment requirements, and be readily adaptable to various magnifications.